I recently had an argument with my friends over the "correctness" of the expression "Silent waters run deep". They said that the correct idiom is supposed to be "Still waters run deep".
However, I have come across the former as well in some of the books I have read. Kindly clarify.
I got 2,230 Google hits on "silent waters run deep," I got 166,000 hits for "still waters run deep." I had never heard "silent waters run deep" until today.